Probably his real hair, and obviously a bald spot too.
However, the sideburns are grey because that's the only part he does NOT dye.
Many stylists (and you being so gay, jt, would know this) tell their clients to not dye the sideburns or even actually dye them a different shade of gray, so as to fool people into thinking their hair is not dyed. Because then the person can say 'if I dyed my hair, don't you think I would do my sideburns too?'